Wireless power transfer systems have been developed for a variety of different applications, including battery charging applications for vehicles, mobile electronic devices, tools, and the like. Such systems can use magnetically coupled resonant circuits to transfer energy. Examples of such wireless power transfer systems are described in U.S. Pat. No. 8,531,059 and U.S. Patent Application Publication No. 2013/0249479.
An example of control of a wireless power transfer system is described in U.S. patent application Ser. No. 14/323,436, entitled WIRELESS POWER TRANSFER SYSTEMS USING LOAD FEEDBACK, filed Jul. 3, 2014.
U.S. patent application Ser. No. 14/143,505 entitled METHODS, CIRCUITS AND ARTICLES OF MANUFACTURE FOR CONFIGURING DC OUTPUT FILTER CIRCUITS, filed Dec. 30, 2013, describes wireless power transfer systems having a transmitter including a rectifier that receives power from an AC power source, an inverter circuit that generates a higher frequency AC output voltage from a DC output produced by the rectifier, and a first resonant circuit coupled to an output of the inverter circuit. A receiver includes a second resonant circuit including a coil that is configured to be placed in close proximity to a coil of the first resonant circuit and a rectifier circuit that produces a DC output from an AC output produced by the second resonant circuit.